Change in coreboot[master]: soc/intel/alderlake: Add support for external clock buffer

[EricR Lai (Code Review)]

Attention is currently required from: Furquan Shaikh, Tim Wawrzynczak, Subrata Banik, Angel Pons, Patrick Rudolph.
EricR Lai has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/50162 )

Change subject: soc/intel/alderlake: Add support for external clock buffer
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Patch Set 1:

(1 comment)

Commit Message:

https://review.coreboot.org/c/coreboot/+/50162/comment/c116bae5_94f2799b 
PS1, Line 9: 3 CLKSRC using external clock buffer.
           : CLKSRC 6 provides feed clock to discrete buffer for further
           : distribution to platform.
> Thanks Angel, your understanding is very valid. This part is assume closed. […]

Could you share the schematic to me, just for the external clock part. PD account or my company account is fine.